1. Field of the Invention
The present invention relates to a stereoscopic projector for enhancing the using efficiency of the beam from a light source and removing a keystoning phenomenon that a picture is distorted on a screen to prevent the eye-strain of viewers.
2l . Description of the Prior Art
Various types of stereoscopic projectors are well known in the art. Such stereoscopic projectors include two projectors arranged in parallel so that image from a liquid crystal display (hereinafter "LCD") panel or a slide film is projected on a screen by each light source. As shown in FIG. 1, one of such stereoscopic projectors comprises spherical reflective mirrors 1 and 1', lamps 2 and 2', condenser members 3 and 3', LCD panels 4 and 4', and projection lenses 5 and 5'.
In the conventional stereoscopic projector, the stereoscopic picture is obtained by making the polarizing directions of projected beams perpendicular to each other by using two projectors, and then the picture from a right projector is watched only with right eye of a viewer and the picture from a left projector is watched only with left eye of a viewer, respectively.
In the conventional projector, the lamps 2 and 2' are independently operated and when the beams from the lamps 2 and 2' pass through the LCD panels 4 and 4', the beams are polarized in the direction of a polarizing axis of polarizing plates 41 attached to the LCD panels 4 and 4'. At this time, a half of the beams condensed by the condenser members 3 and 3' is decreased before having passed through the LCD panels 4 and 4' by one polarizing plate 41 which is located at the light source side. A loss of light occurs due to a part of light being absorbed as a heat to the polarizing plate 41 of the light source side, thereby necessitating a separate cooling device to increase the cooling efficiency at the LCD panels 4 and 4'.
Furthermore, the conventional projector involves another problems that a keystoning phenomenon that two pictures are distorted, is produced when projecting an image on the screen 6 on account of using two projectors and resulting in eyestrain of viewers, and it also requires a complicated projection lens driving system to make two pictures accord to each other.